1. Field Pertinent to the Invention
The present invention relates to a technical field of a positioning apparatus and a navigation apparatus, and a positioning method and a navigation method. More particularly, the present invention relates to a positioning apparatus which measures a current position of a vehicle by the use of the position measuring information transmitted from GPS (Global Positioning System) satellite which has been launched in cosmic space and supports movement of the vehicle and a positioning method, and a navigation apparatus including the current positioning apparatus and a navigation method including the current positioning method.
2. Related Background Art
Recently, it has been widely generalized to specify a current position of a movable body such as a vehicle or the like by the use of the position measuring information transmitted from a positioning satellite such as the above described GPS satellite to be used for specifying a position of the movable body on the earth.
According to the above described conventional positioning processing by the use of the position measuring information, specifically, a current position at the present time has been calculated by using both of an estimated position at the present time which is obtained from the current position calculated by the former positioning processing on the base of a predetermined estimation method and a measured position at the present time which is calculated only by using the position measuring information received at the present time. Then, finally, this calculated current position is displayed as a current position of the vehicle, which is calculated by the use of the above described GPS satellite, for example, on a display in the vehicle.
On the one hand, as the first related background art, the reception of the position measuring information to be transmitted from the above described positioning satellite is interrupted, for example, while the vehicle is moving in a tunnel or the like, so that it becomes impossible to calculate the above described measured position.
Therefore, according to the above described conventional positioning processing, if the position measuring information has been not obtained during a period which is longer than a predetermined threshold value (more specifically, for example, three seconds), assuming that accuracy of the above described estimated position during a period in which this position measuring information has been not obtained, a reset process has been performed in such a manner that an estimated position to be calculated on the basis of a current position before the interruption is ignored and the above described measured position to be obtained after the reception of the position measuring information restarts is defined as a current position of the movable body at the present time. Further, according to the conventional positioning processing, the above described threshold value comprises a predetermined value as a fixed value.
On the other hand, as the second related background art, when a position includes a plan position and an altitude of the movable body, according to the above described conventional positioning processing, in the case where degrees of accuracy of an estimated position and a positioning position are lowered, the reset processing has been performed in such a manner that the estimated position and the positioning position, which were calculated at precedence timing, are ignored and the estimated position just after obtained is defined as a current position of the movable body in that time.
Alternatively, it is assumed that the degrees of the accuracy of the above estimated position and the positioning position indicating timing, at which this reset processing starts, are detected to be lowered specifically when a difference between the altitude information calculated as the above estimated position (namely, the altitude information of a vehicle calculated only on the basis of the position measuring information) and the altitude information included in the above estimated information (namely, the estimated altitude information calculated as the estimated position) becomes not less than a predetermined threshold value. The present threshold value is defined as a higher value in some measure in association with an error to be principally included in the position measuring information.
However, according to the conventional positioning processing having the above described constitution of the first related background art, since the threshold value comprises a predetermined value as a fixed value, the following scopes for improvement have been occur.
In other words, at first, under the condition that the position measuring information having a low degree of accuracy is only obtained after the time shown by the threshold value has been passed, the positioning position having an extremely low degree of accuracy is identified as a current position. Accordingly, this involves a scope for improvement such that the accuracy of the current position also becomes extremely low.
Additionally, secondly, under the condition that the new position measuring information having a high degree of accuracy is obtained before the time shown by the threshold value has been passed, the above described positioning position is calculated in such a manner that the estimated position when the time shown by the threshold value has been passed is added to the positioning position on the basis of this position measuring information having a high degree of accuracy. Accordingly, this involves a scope for improvement such that, despite the positioning position having a high degree of accuracy has been obtained, only the current position having a degree of accuracy which is lower than that of the positioning position is calculated.
On the other hand, according to the conventional positioning processing having the above described constitution of the second related background art, the above threshold value comprises a fixed value and a high value in some measure, so that this involves a scope for improvement such that there is a case that the reset processing does not start when the need arises.
More specifically, for example, if the degrees of the accuracy of the estimated position and the positioning position are decreased, the reset processing on the basis of the difference in the altitude information does not start even when the positional error is obviously included in the current position of the vehicle which is displayed on the display. As a result, there is a case that the current positional error becomes larger.
Therefore, the present invention has been made taking the foregoing scopes for improvement into consideration, an object of which is to provide a positioning apparatus capable of calculating a current position at a higher degree of accuracy compared to a conventional case by the positioning position and the estimated position and a positioning method, and a navigation apparatus including the current positioning apparatus and a navigation method including the current positioning method.
The above object of the present invention can be achieved by a positioning apparatus. In one aspect of the present invention, there is provided a positioning apparatus which measures a current position of a movable body on the basis of a position information indicating a position of said movable body which was measured in the past by the use of a position measuring information transmitted from a positioning satellite. The positioning apparatus is provided with: a detecting device which detects a receiving condition of said position measuring information; a measuring device which ignores said position information which was obtained in the past when a precision of said position measuring information is decided to be deteriorated on the basis of a threshold value and measures said current position of said movable body by the use of said position measuring information which is received at the present time; and a control device which controls said threshold value on the basis of said detected receiving condition.
According to this aspect, the threshold value is controlled on the basis of the detected receiving condition of the position measuring information, so that it is possible to control whether the past position information is reflected on the current position information depending on the receiving condition of the current position measuring information, namely, its reliability or not. As a result, it is possible to measure the current position more precisely.
In another aspect of the positioning apparatus, said positioning apparatus further comprises a scaling device which measures a length of a period of time that the positioning by the use of said position measuring information has been impossible on the basis of said detected receiving condition; said measuring device ignores said position information which was obtained in the past when said measured length becomes not less than said threshold value and measures said current position of said movable body by the use of said position measuring information which is received at the present time.
According to this aspect, in the case of positioning the current position by the use of the position measuring information which is received at the present time by ignoring the previously obtained position information when the positioning by the use of the position measuring information only during time longer than the threshold value becomes impossible, the threshold value is controlled depending on the receiving condition of the position measuring information, so that it is possible to control whether the past position information is reflected on the current position information depending on the receiving condition of the current position measuring information, namely, its reliability or not. As a result, it is possible to measure the current position more precisely.
In further aspect of the positioning apparatus, said control device controls said threshold value when said receiving condition is deteriorated.
According to this aspect, when the receiving condition of the position measuring information is deteriorated, namely, when the reliability of the position measuring information is deteriorated, the threshold value is controlled, so that it is possible to measure the current position of the movable body more precisely.
In further aspect of the positioning apparatus, said detecting device, in said receiving condition, detects whether a influence of a multipath is received or not and; said control device controls said threshold value so as to be increased when said influence of said multipath is received.
According to this aspect, the threshold value is increased when receiving the influence by a multipath, so that it is possible to use the previous position information during longer time when the degree of accuracy of the position measuring information is low. As a result, it is possible to improve the degree of accuracy of the current position in the case where the degree of the accuracy of the position measuring information is low.
In further aspect of the positioning apparatus, said detecting device detects the first accuracy information which indicates a degree of accuracy of said position measuring information itself transmitted with being included in said position measuring information and the second accuracy information which indicates the measuring accuracy of the position on the basis of a spatial arrangement relation of a plurality of said positioning satellites; and said control device controls said threshold value to be decreased when the accuracy indicated by the first accuracy information is higher than a predetermined first threshold value and the accuracy indicated by the second accuracy information is higher than a predetermined second threshold value.
According to this aspect, the threshold value is decreased when the accuracy shown by the first accuracy information is higher than the first accuracy threshold and the accuracy shown by the second accuracy information is higher than the second accuracy threshold, so that a period of time that the previous position information has been used is shortened when the accuracy of the position measuring information is higher and the current position is measured by the use of the current position measuring information. As a result, it is possible to measure the current position with a high degree of accuracy in the case where the accuracy of the position measuring information is high.
In further aspect of the positioning apparatus, said positioning apparatus is provided with: an altitude information generating device which generates an altitude information indicating the altitude of said movable body by the use of said position measuring information; an altitude estimating device which estimates the altitude of said movable body at the present time from the past position information including a plan position and an altitude of said movable body measured in the past as said position information; said measuring device ignores said past position information when a difference between the altitude indicated by said altitude information and the estimated altitude becomes not less than said threshold value and measures a plan position and an altitude of said movable body at the present time by the use of said position measuring information which is received at the present time.
According to this aspect, in the case of measuring a present plan position and a present altitude by the use of the position measuring information which is received at the present time by ignoring the past position information when a difference between an altitude indicated by the positioning altitude information and the estimated altitude becomes not less than a threshold value, the threshold value is controlled depending on the receiving condition of the position measuring information, so that it is possible to control whether the previous position information is reflected on the current position information including the altitude depending on the receiving condition of the current position measuring information, namely, its reliability or not. As a result, it is possible to measure the present plan position and the present altitude more precisely.
In further aspect of the positioning apparatus, said detecting device, as said receiving condition, detects whether an influence of a multipath is received or not and an accuracy information indicating a degree of accuracy of said position measuring information itself which is transmitted with being included in said position measuring information; and said control device controls said threshold value so as to be decreased when said degree of accuracy indicated by said accuracy information is higher than a predetermined accuracy threshold value and said influence of said multipath is not received.
According to this aspect, the threshold value is decreased when the degree of the accuracy indicated by the accuracy information is high and the influence by a multipath is not received, so that a period of time that the past position information has been used is shortened when the degree of the accuracy of the position measuring information is high and a present plan position and a present altitude are measured by the use of the current position measuring information. As a result, it is possible to measure the present plan position and the present altitude with a higher degree of accuracy in the case where the degree of the accuracy of the position measuring information is high.
The above object of the present invention can be achieved by a navigation apparatus. In one aspect of the present invention, there is provided a navigation apparatus which measures a current position of a movable body on the basis of a position information indicating a position of said movable body which was measured in the past by the use of a position measuring information transmitted from a positioning satellite. The navigation apparatus is provided with: a detecting device which detects a receiving condition of said position measuring information; a scaling device which measures a length of a period of time that the positioning by the use of said position measuring information has been impossible on the basis of said detected receiving condition; a measuring device ignores said position information which was obtained in the past when said measured length becomes not less than a threshold value and measures said current position of said movable body by the use of said position measuring information which is received at the present time; a control device which controls said threshold value on the basis of said detected receiving condition; and a supporting device which supports the movement of said movable body on the basis of said measured position.
According to this invention, it is possible to measure the current position with a high degree of accuracy depending on the receiving condition of the position measuring information and support the movement of the vehicle.
In another aspect of the navigation apparatus is provided with: a detecting device which detects a receiving condition of said position measuring information; an altitude information generating device which generates an altitude information indicating the altitude of said movable body by the use of said position measuring information; an altitude estimating device which estimates the altitude of said movable body at the present time from the past position information including a plan position and an altitude of said movable body measured in the past as said position information; a measuring device which ignores said past position information when a difference between the altitude indicated by said altitude information and the estimated altitude becomes not less than a threshold value and measures a plan position and an altitude of said movable body at the present time by the use of said position measuring information which is received at the present time; a control device which controls said threshold value on the basis of said detected receiving condition; and a supporting device which supports the movement of the movable body on the basis of said measured position.
According to this invention, it is possible to measure the current position with a high degree of accuracy depending on the receiving condition of the position measuring information and support the movement of the vehicle.
The above object of the present invention can be achieved by a positioning method. In one aspect of the present invention, there is provided a positioning method of measuring a current position of a movable body on the basis of a position information indicating a position of said movable body which was measured in the past by the use of a position measuring information transmitted from a positioning satellite. The positioning method is provided with: a detecting process of detecting a receiving condition of said position measuring information; a measuring process of ignoring said position information which was obtained in the past when a precision of said position measuring information is decided to be deteriorated on the basis of a threshold value and measures said current position of said movable body by the use of said position measuring information which is received at the present time; and a controlling process of controlling said threshold value on the basis of said detected receiving condition.
According to this aspect, the threshold value is controlled on the basis of the detected receiving condition of the position measuring information, so that it is possible to control whether the past position information is reflected on the current position information depending on the receiving condition of the current position measuring information, namely, its reliability or not. As a result, it is possible to measure the current position more precisely.
In further aspect of the positioning method, said positioning method further comprises a scaling process of measuring a length of a period of time that the positioning by the use of said position measuring information has been impossible on the basis of said detected receiving condition; in said measuring process, said position information which was obtained in the past is ignored when said measured length becomes not less than said threshold value and said current position of said movable body is measured by the use of said position measuring information which is received at the present time.
According to this aspect, in the case of positioning the current position by the use of the position measuring information which is received at the present time by ignoring the previously obtained position information when the positioning by the use of the position measuring information only during time longer than the threshold value becomes impossible, the threshold value is controlled depending on the receiving condition of the position measuring information, so that it is possible to control whether the past position information is reflected on the current position information depending on the receiving condition of the current position measuring information, namely, its reliability or not. As a result, it is possible to measure the current position more precisely.
In further aspect of the positioning method, in said controlling process, said threshold value is controlled when said receiving condition is deteriorated.
According to this aspect, when the receiving condition of the position measuring information is deteriorated, namely, when the reliability of the position measuring information is deteriorated, the threshold value is controlled, so that it is possible to measure the current position of the movable body more precisely.
In further aspect of the positioning method, in said detecting process, in said receiving condition, whether a influence of a multipath is received or not is detected and; in said controlling process, said threshold value is controlled so as to be increased when said influence of said multipath is received.
According to this aspect, the threshold value is increased when receiving the influence by a multipath, so that it is possible to use the previous position information during longer time when the degree of accuracy of the position measuring information is low. As a result, it is possible to improve the degree of accuracy of the current position in the case where the degree of the accuracy of the position measuring information is low.
In further aspect of the positioning method, in said detecting process, the first accuracy information which indicates a degree of accuracy of said position measuring information itself transmitted with being included in said position measuring information and the second accuracy information which indicates the measuring accuracy of the position on the basis of a spatial arrangement relation of a plurality of said positioning satellites are detected; and in said controlling process, said threshold value is controlled to be decreased when the accuracy indicated by the first accuracy information is higher than a predetermined first threshold value and the accuracy indicated by the second accuracy information is higher than a predetermined second threshold value.
According to this aspect, the threshold value is decreased when the accuracy shown by the first accuracy information is higher than the first accuracy threshold and the accuracy shown by the second accuracy information is higher than the second accuracy threshold, so that a period of time that the previous position information has been used is shortened when the accuracy of the position measuring information is higher and the current position is measured by the use of the current position measuring information. As a result, it is possible to measure the current position with a high degree of accuracy in the case where the accuracy of the position measuring information is high.
In further aspect of the positioning method, said positioning method is provided with: an altitude information generating process of generating an altitude information indicating the altitude of said movable body by the use of said position measuring information; an altitude estimating process of estimating the altitude of said movable body at the present time from the past position information including a plan position and an altitude of said movable body measured in the past as said position information; in said measuring process, said past position information is ignored when a difference between the altitude indicated by said altitude information and the estimated altitude becomes not less than said threshold value and a plan position and an altitude of said movable body at the present time is measured by the use of said position measuring information which is received at the present time.
According to this aspect, in the case of measuring a present plan position and a present altitude by the use of the position measuring information which is received at the present time by ignoring the past position information when a difference between an altitude indicated by the positioning altitude information and the estimated altitude becomes not less than a threshold value, the threshold value is controlled depending on the receiving condition of the position measuring information, so that it is possible to control whether the previous position information is reflected on the current position information including the altitude depending on the receiving condition of the current position measuring information, namely, its reliability or not. As a result, it is possible to measure the present plan position and the present altitude more precisely.
In further aspect of the positioning method, in said detecting process, as said receiving condition, whether an influence of a multipath is received or not and an accuracy information indicating a degree of accuracy of said position measuring information itself which is transmitted with being included in said position measuring information are detected; and in said controlling process, said threshold value is controlled so as to be decreased when said degree of accuracy indicated by said accuracy information is higher than a predetermined accuracy threshold value and said influence of said multipath is not received.
According to this aspect, the threshold value is decreased when the degree of the accuracy indicated by the accuracy information is high and the influence by a multipath is not received, so that a period of time that the past position information has been used is shortened when the degree of the accuracy of the position measuring information is high and a present plan position and a present altitude are measured by the use of the current position measuring information. As a result, it is possible to measure the present plan position and the present altitude with a higher degree of accuracy in the case where the degree of the accuracy of the position measuring information is high.
The above object of the present invention can be achieved by a navigation method. In one aspect of the present invention, there is provided a navigation method of measuring a current position of a movable body on the basis of a position information indicating a position of said movable body which was measured in the past by the use of a position measuring information transmitted from a positioning satellite. The navigation method is provided with: a detecting process of detecting a receiving condition of said position measuring information; a scaling process of measuring a length of a period of time that the positioning by the use of said position measuring information has been impossible on the basis of said detected receiving condition; a measuring process of ignoring said position information which was obtained in the past when said measured length becomes not less than a threshold value and said current position of said movable body is measured by the use of said position measuring information which is received at the present time; a controlling process of controlling said threshold value on the basis of said detected receiving condition; and a supporting process of supporting the movement of said movable body on the basis of said measured position.
According to this invention, it is possible to measure the current position with a high degree of accuracy depending on the receiving condition of the position measuring information and support the movement of the vehicle.
In another aspect of the navigation method is provided with: a detecting process of detecting a receiving condition of said position measuring information; an altitude information generating process of generating an altitude information indicating the altitude of said movable body by the use of said position measuring information; an altitude estimating process of estimating the altitude of said movable body at the present time from the past position information including a plan position and an altitude of said movable body measured in the past as said position information; a measuring process of ignoring said position information which was obtained in the past when a difference between the altitude indicated by said altitude information and the estimated altitude becomes not less than a threshold value and a plan position and an altitude of said movable body at the present time is measured by the use of said position measuring information which is received at the present time; a controlling process of controlling said threshold value on the basis of said detected receiving condition; and a supporting process of supporting the movement of the movable body on the basis of said measured position.
According to this invention, it is possible to measure the current position with a high degree of accuracy depending on the receiving condition of the position measuring information and support the movement of the vehicle.